Class EmptyBlockCheck
- java.lang.Object
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- com.puppycrawl.tools.checkstyle.api.AutomaticBean
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- com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
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- com.puppycrawl.tools.checkstyle.api.AbstractCheck
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- com.puppycrawl.tools.checkstyle.checks.blocks.EmptyBlockCheck
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- All Implemented Interfaces:
Configurable
,Contextualizable
public class EmptyBlockCheck extends AbstractCheck
Checks for empty blocks. This check does not validate sequential blocks.
Sequential blocks won't be checked. Also, no violations for fallthrough:
switch (a) { case 1: // no violation case 2: // no violation case 3: someMethod(); { } // no violation default: break; }
NOTE: This check processes LITERAL_CASE and LITERAL_DEFAULT separately. Verification empty block is done for single nearest
case
ordefault
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Property
option
- specify the policy on block contents. Type iscom.puppycrawl.tools.checkstyle.checks.blocks.BlockOption
. Default value isstatement
. -
Property
tokens
- tokens to check Type isjava.lang.String[]
. Validation type istokenSet
. Default value is: LITERAL_WHILE, LITERAL_TRY, LITERAL_FINALLY, LITERAL_DO, LITERAL_IF, LITERAL_ELSE, LITERAL_FOR, INSTANCE_INIT, STATIC_INIT, LITERAL_SWITCH, LITERAL_SYNCHRONIZED.
To configure the check:
<module name="EmptyBlock"/>
Example:
public class Test { private void emptyLoop() { for (int i = 0; i < 10; i++) { // violation } try { // violation } catch (Exception e) { // ignored } } }
To configure the check for the
text
policy and onlytry
blocks:<module name="EmptyBlock"> <property name="option" value="text"/> <property name="tokens" value="LITERAL_TRY"/> </module>
Example:
public class Test { private void emptyLoop() { for (int i = 0; i < 10; i++) { // ignored } // violation on next line try { } catch (Exception e) { // ignored } } }
To configure the check for default in switch block:
<module name="EmptyBlock"> <property name="tokens" value="LITERAL_DEFAULT"/> </module>
Example:
public class Test { private void test(int a) { switch (a) { case 1: someMethod(); default: // OK, as there is no block } switch (a) { case 1: someMethod(); default: {} // violation } } }
Parent is
com.puppycrawl.tools.checkstyle.TreeWalker
Violation Message Keys:
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block.empty
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block.noStatement
- Since:
- 3.0
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Nested Class Summary
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Nested classes/interfaces inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
AutomaticBean.OutputStreamOptions
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Field Summary
Fields Modifier and Type Field Description static java.lang.String
MSG_KEY_BLOCK_EMPTY
A key is pointing to the warning message text in "messages.properties" file.static java.lang.String
MSG_KEY_BLOCK_NO_STATEMENT
A key is pointing to the warning message text in "messages.properties" file.private BlockOption
option
Specify the policy on block contents.
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Constructor Summary
Constructors Constructor Description EmptyBlockCheck()
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description private boolean
checkIsAllLinesAreWhitespace(int lineFrom, int lineTo)
Checks is all lines from 'lineFrom' to 'lineTo' (exclusive) contain whitespaces only.private static DetailAST
findLeftCurly(DetailAST ast)
Calculates the left curly corresponding to the block to be checked.int[]
getAcceptableTokens()
The configurable token set.int[]
getDefaultTokens()
Returns the default token a check is interested in.int[]
getRequiredTokens()
The tokens that this check must be registered for.private boolean
hasText(DetailAST slistAST)
Checks if SLIST token contains any text.void
setOption(java.lang.String optionStr)
Setter to specify the policy on block contents.void
visitToken(DetailAST ast)
Called to process a token.-
Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractCheck
beginTree, clearViolations, destroy, finishTree, getFileContents, getFilePath, getLine, getLineCodePoints, getLines, getTabWidth, getTokenNames, getViolations, init, isCommentNodesRequired, leaveToken, log, log, log, setFileContents, setTabWidth, setTokens
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Methods inherited from class com.puppycrawl.tools.checkstyle.api.AbstractViolationReporter
finishLocalSetup, getCustomMessages, getId, getMessageBundle, getSeverity, getSeverityLevel, setId, setSeverity
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Methods inherited from class com.puppycrawl.tools.checkstyle.api.AutomaticBean
configure, contextualize, getConfiguration, setupChild
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Field Detail
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MSG_KEY_BLOCK_NO_STATEMENT
public static final java.lang.String MSG_KEY_BLOCK_NO_STATEMENT
A key is pointing to the warning message text in "messages.properties" file.- See Also:
- Constant Field Values
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MSG_KEY_BLOCK_EMPTY
public static final java.lang.String MSG_KEY_BLOCK_EMPTY
A key is pointing to the warning message text in "messages.properties" file.- See Also:
- Constant Field Values
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option
private BlockOption option
Specify the policy on block contents.
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Constructor Detail
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EmptyBlockCheck
public EmptyBlockCheck()
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Method Detail
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setOption
public void setOption(java.lang.String optionStr)
Setter to specify the policy on block contents.- Parameters:
optionStr
- string to decode option from- Throws:
java.lang.IllegalArgumentException
- if unable to decode
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getDefaultTokens
public int[] getDefaultTokens()
Description copied from class:AbstractCheck
Returns the default token a check is interested in. Only used if the configuration for a check does not define the tokens.- Specified by:
getDefaultTokens
in classAbstractCheck
- Returns:
- the default tokens
- See Also:
TokenTypes
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getAcceptableTokens
public int[] getAcceptableTokens()
Description copied from class:AbstractCheck
The configurable token set. Used to protect Checks against malicious users who specify an unacceptable token set in the configuration file. The default implementation returns the check's default tokens.- Specified by:
getAcceptableTokens
in classAbstractCheck
- Returns:
- the token set this check is designed for.
- See Also:
TokenTypes
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getRequiredTokens
public int[] getRequiredTokens()
Description copied from class:AbstractCheck
The tokens that this check must be registered for.- Specified by:
getRequiredTokens
in classAbstractCheck
- Returns:
- the token set this must be registered for.
- See Also:
TokenTypes
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visitToken
public void visitToken(DetailAST ast)
Description copied from class:AbstractCheck
Called to process a token.- Overrides:
visitToken
in classAbstractCheck
- Parameters:
ast
- the token to process
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hasText
private boolean hasText(DetailAST slistAST)
Checks if SLIST token contains any text.- Parameters:
slistAST
- aDetailAST
value- Returns:
- whether the SLIST token contains any text.
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checkIsAllLinesAreWhitespace
private boolean checkIsAllLinesAreWhitespace(int lineFrom, int lineTo)
Checks is all lines from 'lineFrom' to 'lineTo' (exclusive) contain whitespaces only.- Parameters:
lineFrom
- check from this line numberlineTo
- check to this line numbers- Returns:
- true if lines contain only whitespaces
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findLeftCurly
private static DetailAST findLeftCurly(DetailAST ast)
Calculates the left curly corresponding to the block to be checked.- Parameters:
ast
- aDetailAST
value- Returns:
- the left curly corresponding to the block to be checked
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